pcc file that contains the mesh you want to extract. Open ME3Explorer and go to Meshplorer (Developer Tools > Meshplorer).I already wrote a tutorial about how to replace meshes in-game, but here is a guide on how to extract them and edit them:
You can do a lot with Mesh Modding, including replacing characters entirely – here’s an example where I replaced Jacob in the Citadel DLC Party with Mordin: